My overall HVAC system strategy aims to use more complex HVAC service types where needed while using more basic HVAC service types where possible. This approach is intended to balance overall project costs with building performance and HVAC system efficiency.
Because my building’s heating loads are relatively modest (located in relatively warm climate), because of the passive solar strategies implemented (north-facing curtain wall and large windows + thermally massive concrete floors), and because of thermal heat associated with people within the building), I decided to rely simply on an air-based heating strategy (delivered thru ducts). I also decided not to rely on heating in certain sections of the building, including terrace/walkways, storage spaces, and utility rooms, all of which have cooling only. Similarly, the stairway areas are vented only.
For the reasons described above, cooling is the primary HVAC obligation associated with my building. I used curtain wall shading on my building’s north faces, as well as highly efficient glazed windows on those faces, to reduce cooling penalties associated with my building. Mechanical cooling is served by cool air delivered through building ducts. Most sections of the building are likely to experience fluctuating demand for cooling (e.g., exhibition spaces, conference rooms, offices, etc., which will be busy sometimes and not busy other times), so I decided to rely on VAV systems. These systems ensure that cooling can be narrowly-tailored to actual needs during specific times. This helps to ensure that cooling can be prioritized only where/when it is needed most and is not running at full blast at all times.
Other areas rely instead on split systems with mechanical ventilation and cooling. These areas include restrooms, the cafe areas, and the food preparation area. All of these areas require mechanical ventilation and cooling given the need for ventilation to maintain sanitary and comfortable conditions. This approach also helps reduce ductwork obligations.
For the purpose of this exercise I decided to focus most of my efforts on a more detailed approach to the top floor of my building rather than a very basic approach to all floors of the building. For the top floor I modeled VAV systems, return air ducts, and (tried to!) connect my ducts to the air handlers in the top floor mechanical room.